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Hydrodynamic Chromatography On-line with Single Particle -Inductively Coupled Plasma – Mass Spectrometry for Ultratrace Detection of Metal-Containing Nanoparticles
Citation:
PERGANTIS, S. A., T. L. JONES-LEPP, AND E. M. HEITHMAR. Hydrodynamic Chromatography On-line with Single Particle -Inductively Coupled Plasma – Mass Spectrometry for Ultratrace Detection of Metal-Containing Nanoparticles. Analytical Chemistry. American Chemical Society, Washington, DC, 84(15):6454-6462, (2012).
Impact/Purpose:
Because of their unique physicochemical properties, nanomaterials are finding use in an increasing number of consumer products.1,2,3 Silver (Ag) nanoparticles (NPs) have already been introduced in over 100 products, ranging from nutritional supplements, personal care products, biocide coatings, clothing, toys as well as dispersed biocides in washing machines.4,5,6,7 Other nanomaterials, including TiO2<.lSUB>, ZnO, Au, CeO, carbon nanotubes, and fullerenes, are found in a wide range of consumer products.7 Recent reports show over 1300 consumer products contain engineered nanomaterials.7 This, of course, is very attractive to consumers as products with unique properties and improved quality are continuously becoming available. In fact, such developments are hinting that a nanotechnology based revolution is rapidly approaching.
Description:
Nanoparticle (NP) determination has recently gained considerable interest since a growing number of engineered NPs are being used in commercial products. As a result, their potential to enter the environment and biological systems is increasing. In this study, we report on the development of a hyphenated analytical technique for the detection and characterization of metal-containing NPs, i.e. their metal mass fraction, size and number concentration. Hydrodynamic chromatography (HDC), suitable for sizing NPs within the range of 5 to 300 nm, was coupled on-line to inductively coupled plasma mass spectrometry (ICPMS), providing for an extremely selective and sensitive analytical tool for the detection of NPs. However, a serious drawback when operating the ICPMS in its conventional mode is that it does not provide data regarding NP number concentrations, and; thus, any information about the metal mass fraction of individual NPs. To address this limitation, we developed single particle (SP) ICPMS coupled on-line HDC as an analytical approach suitable for simultaneously determining NP size, NP number concentration, and NP metal content. Gold (Au) NPs of various sizes were used as the model system. To achieve such characterization metrics, three calibrations were required and used to convert ICPMS signal spikes into NPs injected, NP retention time on the HDC column to NP size, and ions detected per signal spike or per NP to metal content in each NP. Two calibration experiments were required in order to make all three calibrations. Contour plots were constructed in order to provide for a convenient and most informative viewing of this data. An example of this novel analytical approach was demonstrated for the analysis of Au-NPs that had been spiked into drinking water at the ng Au L-1 level. The described technique gave limits of detection for 60 nm Au-NPs of approximately 2.2 ng Au L-1 or expressed in terms of NP number concentrations 600 Au-NPs mL-1.